Please varify if the power supply to the PSoC4200 TQFP-44 chip has been connected properly.
(See the attachment)
 Do we have to connect the VCCD pin to a voltage supply externally, or just bypass it?
 What is the function of XRES pin?
 Normally, on other MCUs there is only a VDD pin and not VCC. Why VDD and VCC both in PSOC? What is the purpose?
1) As Dana already wrote, Vccd is internal and should be decoupled only
3) there is no Vcc pin on the PSoC, only Vdd pins (at least for power supply). Both Vdd and Vcc denote power supply pins, with 'd' being for 'drain' and 'c' being for 'collector' - so its a reference to the internal technology. Vccd means 'Vcc for the digital sub-system' (the MCU core)
Additionally: its OK to connect Vdda and Vddd together. But to improve analog performance, it is a good idea to connect each with a ferrite bead / a small inductor to the power supply (to decouple them from each other).
Maybe look at AN88619 - PSoC4 hardware design considerations.